wdmd(8) [debian man page]

WDMD(8) 						      System Manager's Manual							   WDMD(8)

NAME

       wdmd - watchdog multiplexing daemon

SYNOPSIS

       wdmd [OPTIONS]

DESCRIPTION

       This  daemon opens /dev/watchdog and allows multiple independent sources to detmermine whether each KEEPALIVE is done.  Every test interval
       (10 seconds), the daemon tests each source.  If any test fails, the KEEPALIVE is not done.  In a standard configuration, the watchdog timer
       will  reset the system if no KEEPALIVE is done for 60 seconds ("fire timeout").	This means that if single test fails 5-6 times in row, the
       watchdog will fire and reset the system.  With multiple test sources, fewer separate failures back to back can also cause a reset, e.g.

       T seconds, P pass, F fail
       T00: test1 P, test2 P, test3 P: KEEPALIVE done
       T10: test1 F, test2 F, test3 P: KEEPALIVE skipped
       T20: test1 F, test2 P, test3 P: KEEPALIVE skipped
       T30: test1 P, test2 F, test3 P: KEEPALIVE skipped
       T40: test1 P, test2 P, test3 F: KEEPALIVE skipped
       T50: test1 F, test2 F, test3 P: KEEPALIVE skipped
       T60: test1 P, test2 F, test3 P: KEEPALIVE skipped
       T60: watchdog fires, system resets

       (Depending on timings, the system may be reset sometime shortly before T60, and the tests at T60 would not be run.)

       A crucial aspect to the design and function of wdmd is that if any single source does not pass tests for the fire timeout, the watchdog	is
       guaranteed  to fire, regardless of whether other sources on the system have passed or failed.  A spurious reset due to the combined effects
       of multiple failing tests as shown above, is an accepted side effect.

       wdmd will exit if a watchdog driver is not loaded.

       wdmd cannot be used on the system with any other program that needs to open /dev/watchdog, e.g. watchdog(8).

   Test Source: clients
       Using libwdmd, programs connect to wdmd via a unix socket, and send regular messages to wdmd to update an expiry time for their connection.
       Every test interval, wdmd will check if the expiry time for a connection has been reached.  If so, the test for that client fails.

       (Other test sources such as scripts executed each test interval may be added in the future.)

OPTIONS

       -D     Enable debugging to stderr and don't fork.

       -H num Enable (1) or disable (0) high priority features such as realtime scheduling priority and mlockall.
	      Default 1.

								    2011-08-01								   WDMD(8)

Check Out this Related Man Page

WD_KEEPALIVE(8) 					      System Manager's Manual						   WD_KEEPALIVE(8)

NAME

       wd_keepalive - a simplified software watchdog daemon

SYNOPSIS

       wd_keepalive [-c filename|--config-file filename]

DESCRIPTION

       This is a simplified version of the watchdog daemon. If configured so it only opens
	.IR  /dev/watchdog  ,  and keeps writing to it often enough to keep the kernel from resetting, at least once per minute. Each write delays
       the reboot time another minute. After a minute of inactivity the watchdog hardware will cause a reset. In the case of the software watchdog
       the ability to reboot will depend on the state of the machines and interrupts.

       The wd_keepalive daemon can be stopped without causing a reboot if the device /dev/watchdog is closed correctly, unless your kernel is com-
       piled with the CONFIG_WATCHDOG_NOWAYOUT option enabled.

       Under high system load wd_keepalive might be swapped out of memory and may fail to make it back in in time. Under these	circumstances  the
       Linux  kernel will reset the machine. To make sure you won't get unnecessary reboots make sure you have the variable realtime set to yes in
       the configuration file watchdog.conf.  This adds real time support to wd_keepalive: it will lock itself into memory and there should  be no
       problem even under the highest of loads.

       On  system  running  out of memory the kernel will try to free enough memory by killing process. The wd_keepalive daemon itself is exempted
       from this so-called out-of-memory killer.

OPTIONS

       Available command line options are the following:

       -c config-file, --config-file config-file
	      Use config-file as the configuration file instead of the default /etc/watchdog.conf.

FILES

       /dev/watchdog
	      The watchdog device.

       /var/run/wd_keepalive.pid
	      The pid file of the running wd_keepalive.

SEE ALSO

       watchdog.conf(5)

       watchdog(8)

4th Berkeley Distribution					   January 2005 						   WD_KEEPALIVE(8)

Linux and UNIX Man Pages

wdmd(8) [debian man page]

Check Out this Related Man Page